1. J. Famiglietti 1, T. Syed 1, P. Yeh 1,2 and M. Rodell 3 1 Dept. of Earth System Science, University of California,Irvine, USA 2 now at: Institute of Industrial Science, University of Tokyo 3 Hydrological Sciences Branch, NASA Goddard Space Flight Center, Greenbelt, MD, USA in collaboration with D. Chambers, University of Texas at Austin F. Frappart, University of California, Irvine S. Nerem, University of Colorado S. Swenson, National Center for Atmospheric Research I. Velicogna, University of California, Irvine J. Wahr, University of Colorado Terrestrial and Global Hydrology from Satellite Observations of Time-Variable Gravity

2. New applications and understanding of terrestrial and global hydrology Groundwater storage variations Estimating regional and global discharge Emerging trends in terrestrial hydrology Mass changes in Earth’s global water reservoirs Overview

3. Groundwater Storage Changes Using GRACE  S LAND =  S SNOW +  S SW +  S SM +  S GW  S GW  S LAND -  S SNOW -  S SW -  S SM Remove this (  S SNOW +  S SW +  S SM ) from  S LAND … To isolate this (  S GW )  S LAND

4. Mississippi River basin Illinois GRACE groundwater estimate Groundwater well observations GRACE groundwater estimates (smoothed) Yeh et al., 2006 Rodell et al., 2006 Groundwater Storage Changes Using GRACE

5. Swenson et al., 2007, to appear Groundwater Storage Changes Using GRACE

6. Terrestrial water balance  S LAND = P - E- R Atmospheric water balance  W = E - P - divQ Coupled land-atmosphere water balance R =  S LAND -  W - divQ  S LAND : storage change (dS/dt) P: precipitation E: evaporation R: discharge  W: precipitable water storage change (dW/dt) divQ: horizontal water vapor divergence Previously had to assume that  S LAND = 0 and apply at annual time scales Now we have  S LAND so we can compute monthly time series Freshwater Discharge Estimation Using GRACE

7. (a) Lena (b) Ob (c) Yenisei (d) Mackenzie Lena Entire Pan-Arctic Syed et al., 2007b Pan-Arctic discharge estimates Freshwater Discharge Estimation Using GRACE

8. Significance of Pan-Arctic discharge estimates: Covers entire Pan-Arctic region, including ungauged regions Larger than previous scaled, gauge-based estimates for the equivalent time period Implications are that discharge is larger than could be anticipated by scaling up gauge measurement, or that discharge in that region is accelerating, or both Freshwater Discharge Estimation Using GRACE

9. Syed et al., 2007c Drainage region discharge estimates Freshwater Discharge Estimation Using GRACE

10. Syed et al., 2007c Continental discharge estimates Freshwater Discharge Estimation Using GRACE

11. Syed et al., 2007c Land-based and ocean-based estimates agree well Both are well within range of previous estimates Global water balance closure to about 5% Trend (0.5 mm/yr sea level equivalent) has implications for closing GMSLR budget Global discharge estimates Freshwater Discharge Estimation Using GRACE

12. Interannual Variations and Trends in Terrestrial Hydrology from GRACE, 2002-2007 Annual Amplitude (cm)Trend (cm/yr) First global look at magnitude of water storage variations Reveal important information on storage that is typically not captured by models: glacial melt, reservoir release, groundwater mining, etc. Important trends emerging Data are ripe for understanding hydroclimatological variations as well as for data assimilation and for pointing to model enhancements

13. Interannual Variations and Trends in Terrestrial Hydrology from GRACE, 2002-2007

15. Mass Variations in Earth’s Global Water Reservoirs  S GLOBAL =  S OCEAN +  S LAND +  S ICE +  S ATM = 0 We can now track ocean, land and ice changes using a single observing system

16. Monthly storage anomalies as equivalent mean sea level  S OCEAN +  S LAND +  S ICE +  S ATM =  S GLOBAL = 0 Trends (mm/yr) Ocean = 0.35 mm/yr Land = 0.57 mm/yr Greenland = -0.58 mm/yr Antarctica = -0/34 mm/yr Mass Variations in Earth’s Global Water Reservoirs

17. Summary Groundwater storage changes from GRACE are feasible and will improve with improved ancillary data, e.g. remotely sensed snow, surface water and soil moisture. Freshwater discharge estimation from GRACE is currently the only observation-based way to estimate global discharge Emerging trends in continents and global land-ocean-ice demonstrate GRACE capabilities to monitor water storage changes from a single observing system and can help make the case for continuity in the mission

18. Posters Groundwater Comparison of Simulated Groundwater Storage Variations to In Situ Observations and GRACE Terrestrial Water Storage Variations, M. Lo, P. Yeh and J. Famiglietti Discharge Large-Scale Terrestrial Freshwater Discharge Estimation using GRACE, T. Syed, J. Famiglietti, D. Chambers and M. Rodell Decomposition of total water storgage into surface and subsurface components Interannual Variations of River Water Storage from a Multiple Satellite Approach: A case study for the Rio Negro River basin, F. Frappart, F. Papa, J. Famiglietti, C. Prigent, W.B. Rossow, F. Seyler